The boss of BP has admitted that he could lose his job over the oil leak in the Gulf of Mexico.

As engineers try to stop the underwater spill that has been gushing for three weeks, Tony Hayward said he felt no immediate pressure to stand down, but admitted his future depends on how his firm sorted out the crisis.

He told The Times: "I think I will be judged by the response. I don't feel my job is on the line but of course that might change. I will stay here until we have fixed it,."

Mr Hayward, who has based himself in the US to oversee the operation, also revealed he had trouble sleeping and had received hate mail. The 52-year-old added: "The Cabinet now has my personal mobile number and I am getting a lot of calls."

Since the BP-operated Deepwater Horizon rig exploded and sank on April 20 - killing 11 workers - around four million gallons of oil have flooded into the ocean, threatening an environmental catastrophe.

The company is trying to put in place a "top hat" device over the leak and siphon the oil to the surface, following the failure of a similar operation last week. Another option being examined is jamming the leak with golf balls and other debris - an operation dubbed a "junk shot".

My Hayward, a 28-year veteran of BP, has deployed four Hercules aircraft to spray dispersants and more than 500 vessels to skim oil off the surface. A flotilla of around 5,000 small fishing boats is also laying out 1.2 million feet of booms to help to defend the coastlines of under-threat states Louisiana, Mississippi, Alabama and Florida.

BP said on Thursday its cost of trying to stop the leak had now reached around £300 million, with the bill increasing by more than £6 million a day.

The White House said at the start of the crisis that it would keep "its boot at the throat" of the British-based oil giant.

US Congressional investigators have said the device meant to stop oil leaking from the well after the rig explosion was faulty. The blow-out preventer had a hydraulic leak and a failed battery, the investigators said. In the wake of the oil leak, US lawmakers are considering a climate change bill that could allow states to veto offshore drilling plans.